iagainsti

Out of curiousity why are you replacing the motor at 60K miles ? I have a 08 that has been in the shop 3 times the last two weeks for massive valve train rattle and my engine only has 17k on it but sounds like a 82 Pinto running diesel fuel.

llind

Same here... been using 5w30 in my 2010 JK with no issues.

jktoy

I started out using 5w20 and went to 5w30 about a year. I recently went to 10w30. And 10w30 is a world of difference. I don't have ruff starts like before and it is very quiet. I live in north Georgia where it is good and hot in the summer and not too bad in the winter.

Dad

When the 3.8 came out 20 years ago, Chrysler called for 10W30, then revised it to 5W30 in its first decade, then revised it again to 5W20 I think around 2005. For the most part, the engine hasn't changed in any significant way over its 20 year life span that would be affected by oil viscosity (it did get hydraulic roller lifters at some point but even those are not that particular about oil viscosity for it to make any significant difference between 10W30 and 5W20). These engines are old-school, 2-valve OHV engines and are very under-stressed. They are about as finnicky about oil as a lawn mower. You could probably about pour vegetable oil in these motors and get away with it for a while if you had to, they're that simple and low-tech. (kidding, don't actually go pouring vegetable oil in you motors please). My point is, these motors are not at all hard on oil and their dirt-simple design makes them very forgiving as to what you pour into them.



I have used both Castrol GTX and Mobil 1 in the 3.8 (both in the JK and the Caravan) in 5W20, 5W30, and 10W30 viscosities. I noticed a very slight mileage drop going from 5W20 to 5W30 but not enough to worry about. I noticed absolutely no difference in mileage going to 10W30. I changed my oil at the 6000 mile factory recommended interval. As frequently as I change the oil (every 3-5 months) it was just a waste to pour synthetic oil in this simple, low-stress motor. If I anticipated driving only 6000 miles or less per year, then I'd use a synthetic. I experimented with blending 5W20 and 5W30 (btw, the only difference between the two is that the 5W30 just has more viscoity modifier additive in it). I have a bunch of other engines that use 10W30 so in the end I decided to run Castrol GTX 10W30 in both my 3.8 along the rest of my various 10W30-consuming motors to keep things simple. Also the 10W30 significantly reduced the oil consumption in my 3.8's compared to the 5W oils.

Look at the viscosities of these various oils:

Oil type: Castrol GTX 5W20, Castrol GTX 5W30, Castrol GTX 10W30
Viscosity @ 40C cSt: 56.1, 62.1, 61.4
Viscosity @ 100C cSt: 9.1, 10.8, 10.6

Compared to the 5W30, you'll see that the 10W30 actually starts off cold being a little thinner (improves startup) and holds its viscosity about the same at temperature. And compared to the 5W20, it actually holds its visocity better. At operating temp the 10W30's viscosity is in-between to 5W20 and 5W30, which is what I was trying to achieve with the blend anyway. I lose a little bit of startup efficiency compared to the 5W oils but its nominal.

Bottom line: 5W20, 5W30, or 10W30--just pick whatever you like because it really doesn't matter on this simple engine. I'm running 10W30 because I like the "compromise" viscosity it strikes between 5W20 and 5W30, and I already stock it in my garage for other vehicles anyway. Buy a synthetic if it makes you happy and you don't mind paying the premium, but realistically you don't need it on this engine unless you are driving 6000 miles or less per year and only doing annual oil changes. As for 3000 mile oil changes, do it if it makes you happy, but again, it's really not necessary under normal circumstances. But do change conventional oil at no more than 6 months even if you haven't hit 6000 miles yet. 12 months for synthetic and 6 months for conventional, or 6000 miles, whichever comes first. This is a generalization of course since additive packages vary between oil brands, but it's a good simple rule of thumb.

XBlacky08X

10w-30 here for over 10k miles.. No issues whatsoever. Motor is quiet and runs perfect with not a drop of oil consumption

mpco239

Just an FYI- this engine has old roots, true enough, but it is not the same 3.8 that came out in the Dodge Dynasty in (93?). Note that it now produces about 30-40% more power. This engine has continually evolved to perform better and produce less emissions. Its like any family of engines that is supported for @20 years. Rest easy in the knowledge that modern xw-20 oil is very robust (the Mobil 0w-20 SM meets GM 4718M-Corvette spec). I agree the advantages in real world fuel economy are not that high, but I have seen police cars running 5w-20 in the Ford 4.6 2v SOHC (an engine of similar vintage and improvement over time to the 3.8) for hundreds of thousands of very abusive miles with no issues not due to neglect (i know one officer who did not change oil for 11K miles, engine died shortly thereafter). Remember, not only does the engine develop, but so does engine oil/filter technology over time. Today's modern synthetic bears very little resemblance to the SG/H/J oils that existed when the 3.8 was a new design. I believe engineers have this down to a pretty exact science (note that the 3.6 Pentastar specs 5w-30, SRT Hemis and SRT4 Neons etc speced 0w-40, Chevrolet generally specs 5w-30, Toyota specs 0w-20 in Corollas with the 1.8L engine (which is older than dirt). They don't write a blanket policy in support of CAFE standards. It appears to me they let the application dictate the lube with an eye towards using as low a viscosity they can that will meet performance goals. I run Mobil 0w-20.

medic_23387

I was running 5w-20 oil and my engine had a bad ticking noise. I also used about a quart every 3000 miles. Switched to Pennzoil 10w-30 dino, tick is gone and I use no oil now what so ever.

Dad

The 3.3/3.8 internal lubricated parts that matter to oil viscosity have been essentially unchanged over the 20 year span. Improvements in power came from improved intakes and engine management. Look up master rebuild kits for these engines and the oil lubed parts are substantially the same for most model years. The few minor changes to rods, lifters, rockers, etc. are not significant to viscosity anyway. The balance of the changes had to do with mounting bosses for fitting accessories, filter, dipstick tube, revised knock sensors, etc. to accommodate vehicle changes through the years.

You're correct that oil has improved substantially though over this engine's life, and that's where real change is. If they had the shear-stable viscosity improvers they're using today in 5W multi-vis oils, along with the EPA constraints of today, they would have been spec'ing 5W20 for this engine 20 years ago. The oil lubricated parts in this engine haven't changed substantially, but the motor oil has. For this particular motor, I still stand by 10W30 being best suited for it.

Here's one rebuilder article that chronicles the 3.3/3.8 evolution if you want some more info: http://www.enginebuildermag.com/Cont...0000037821.pdf

JKlad

Great info; thanks for including that link!

Unless I missed it, when detailing the difference in parts & components between the different years of manufacture the article didn't mention another important change; the old heavy-duty bearings with lead in the alloy were replaced by the modern "emmissions-friendly" (but not as long-lasting) lead-free ones which will wear quickly if the oil film is lost (as commonly happens during dry starts or low oil levels in the sump due to high oil consumption, both issues the Wrangler's 3.8L in known for). Would explain why spun bearings at 40K miles are far more common on Wrangler motors than the old "bulletproof" minivan units.

Ryan0260

I'm wondering how many on here with oil consumption issues have switched to 10w30 and how much it has helped. Also has it helped with spark knock that can be attributed to bad rings fouling the plugs. And if 10w30 is helping these issues why isn't chrysler making a tsb to change oils?